This invention relates to an ultrasonic tool or instrument particularly, but not exclusively, for use in medical surgical procedures. This invention also relates to an associated process for manufacturing the ultrasonic instrument or tool
Ultrasonic tools have become increasingly used in surgical procedures. Ultrasonic ablation tools are recognized for their accuracy, reliability and ease of use. Ultrasonic bone cutting blades may be designed to facilitate the cutting of bone without damage to adjacent soft tissues. See U.S. Pat. No. 8,343,178. Ultrasonic debriders remove necrotic or otherwise damaged tissue without harming underlying healthy tissue. Ultrasonic instruments such as debriders can have integrated tissue treatment modalities such as high-energy electrical current transmission for cauterization (See U.S. Pat. No. 6,648,839) and low-energy electrical energy transmission for pain suppression (U.S. Patent Application Publication No. 2008/0146921) or stimulating tissue repair (U.S. Pat. No. 8,025,672).
Ultrasonic instruments can incorporate probes with bent shafts for facilitating access to troublesome locations. In some surgical procedures, it is advantageous to have the operative head or end effector portion of the probe angled to one side of the shaft to further facilitate access to a desired surgical site. Typically, in full-wave probe/handpiece assemblies, the center of the shaft bend is located at or near an interior antinode. For symmetric or mostly symmetric probe tip designs, this tends to minimize transverse vibrations and ensures viable ultrasonic operation. A problem arises, however, where the probe head is markedly asymmetric relative to the probe shaft, for example, where a probe shaft carries a highly protruding eccentric shaving head with a large unbalanced mass located off of the central axis. While such an eccentric head design is found by surgeons to be advantageous in effectively undercutting bony anatomy, allowing for deeper cutting, such eccentricity of the probe tends to produce undesirable transverse vibration.